If you have already bought a VC game before on the Wii, you will get a discount. NES games will instead cost $1.00 and SNES games will cost $1.50.
To achieve this new price, you must have already done a Wii to Wii U VC transfer.
Once done, the eShop will actively show you the new price as well as the words "Discount" shown in the listing as well, even before you go to buy it again.

Are the original Wii VC games playable on the Wii U?
Yes. In Wii Mode, all previous Wii VC games are available within Wii Mode after you do the system transfer.

If I already have a Wii VC game and do the upgrade, will it delete it from the Wii mode side?
No. It will continue to be there in Wii mode, even if you buy it again on the Wii U side.

Will Wii VC saves carry over?
No. Saves do not make it over. You will be starting from scratch.

Why isn't XYZ on the upcoming list? I know it's coming.
Even if we know a VC title is coming, I won't add it to the list unless it's upcoming within a few weeks or we know a specific release date.

Aaaaaaaaand three of those have been $0.30 before, one is $0.30 now, Excitebike was free on 3DS for a limited time, and two of those given away on 3DS for Ambassadors. So Super Mario World remains for me...